ao_coreaudio: uncrustify

uncrustify -l C -c TOOLS/uncrustify.cfg --no-backup --replace \
  audio/out/ao_coreaudio.c

Conflicts:
	audio/out/ao_coreaudio.c
ao_coreaudio: move to new libao API

This is just a first pass and the bare minimum to make it compile and work.
SPDIF is untested for lack of hardware.

Conflicts:
	audio/out/ao_coreaudio.c
ao_coreaudio: split ringbuffer in it's own file

This is hopefully the start of something good. ca_ringbuffer_read and
ca_ringbuffer_write can probably cleaned up from all the NULL checks once
ao_coreaudio.c gets simplyfied.

Conflicts:
	audio/out/ao_coreaudio.c